As revenues decline for traditional forms of online advertising, video is emerging as a bright spot for many media companies. It offers an opportunity for long engagement and hefty ad rates — but also a challenge to make it work.

A new study reports that faster internet connections have made viewers more impatient, and that people begin abandoning videos if they don’t load within two seconds. Every second of additional delay results in approximately 6 percent more viewers jumping ship. This chart shows how about 20 percent of viewers are gone after five seconds but that viewers are slightly more patient for long-length videos:

The research comes by way of Ramesh Sitaraman, a computer science professor at UMass Amherst, who studied data representing 23 million video views from 6.7 million unique visitors. The study offers new metrics for streaming views to complement existing studies that describe the “four second rule” — the amount of time people will wait for a webpage to download. It also shows that people will abandon a video faster based on their type of connection (note how people are more patient with mobile) :

The study, which you can read for yourself here (PDF), contains no startling surprises — most of us probably suspected that people give up on watching videos that don’t load. But it does provide useful empirical evidence for companies who must decide how to invest architecture to support their video platforms.

Akamai, a content delivery network that helps sites speed up delivery, provided data and research space for the study but did not influence its findings, according to a spokesperson.